Double-blind, Randomized placebo controlled trial of fulvestrant compared with exemestane after prior nonsteroidal aromatase inhibitor therapy in postmenopausal women with hormone receptor-positive, advanced breast cancer: Results from EFECT

Purpose The third-generation nonsteroidal aromatase inhibitors (AIs) are increasingly used as adjuvant and first-line advanced therapy for postmenopausal, hormone receptor-positive (HR +) breast cancer. Because many patients subsequently experience progression or relapse, it is important to identify agents with efficacy after AI failure. Materials and Methods Evaluation of Faslodex versus Exemestane Clinical Trial (EFECT) is a randomized, double-blind, placebo controlled, multicenter phase III trial of fulvestrant versus exemestane in postmenopausal women with HR + advanced breast cancer (ABC) progressing or recurring after nonsteroidal AI. The primary end point was time to progression (TTP). A fulvestrant loading-dose (LD) regimen was used: 500 mg intramuscularly on day 0, 250 mg on days 14, 28, and 250 mg every 28 days thereafter. Exemestane 25 mg orally was administered once daily. Results A total of 693 women were randomly assigned to fulvestrant (n = 351) or exemestane ( n = 342). Approximately 60% of patients had received at least two prior endocrine therapies. Median TTP was 3.7 months in both groups ( hazard ratio = 0.963; 95% CI, 0.819 to 1.133; P = .6531). The overall response rate ( 7.4% v 6.7%; P = .736) and clinical benefit rate ( 32.2% v 31.5%; P = .853) were similar between fulvestrant and exemestane respectively. Median duration of clinical benefit was 9.3 and 8.3 months, respectively. Both treatments were well tolerated, with no significant differences in the incidence of adverse events or quality of life. Pharmacokinetic data confirm that steady-state was reached within 1 month with the LD schedule of fulvestrant. Conclusion Fulvestrant LD and exemestane are equally active and well-tolerated in a meaningful proportion of postmenopausal women with ABC who have experienced progression or recurrence during treatment with a nonsteroidal AI.

Fulvestrant with or without selumetinib, a MEK 1/2 inhibitor, in breast cancer progressing after aromatase inhibitor therapy: A multicentre randomised placebo-controlled double-blind phase II trial, SAKK 21/08.

BACKGROUND: Second line endocrine therapy has limited antitumour activity. Fulvestrant inhibits and downregulates the oestrogen receptor. The mitogen-activated protein kinase (MAPK) pathway is one of the major cascades involved in resistance to endocrine therapy. We assessed the efficacy and safety of fulvestrant with selumetinib, a MEK 1/2 inhibitor, in advanced stage breast cancer progressing after aromatase inhibitor (AI). PATIENTS AND METHODS: This randomised phase II trial included postmenopausal patients with endocrine-sensitive breast cancer. They were ramdomised to fulvestrant combined with selumetinib or placebo. The primary endpoint was disease control rate (DCR) in the experimental arm. ClinicalTrials.gov Indentifier: NCT01160718. RESULTS: Following the planned interim efficacy analysis, recruitment was interrupted after the inclusion of 46 patients (23 in each arm), because the selumetinib-fulvestrant arm did not reach the pre-specified DCR. DCR was 23% (95% confidence interval (CI) 8-45%) in the selumetinib arm and 50% (95% CI 27-75%) in the placebo arm. Median progression-free survival was 3.7months (95% CI 1.9-5.8) in the selumetinib arm and 5.6months (95% CI 3.4-13.6) in the placebo arm. Median time to treatment failure was 5.1 (95% CI 2.3-6.7) and 5.6 (95% CI 3.4-10.2) months, respectively. The most frequent treatment-related adverse events observed in the selumetinib-fulvestrant arm were skin disorders, fatigue, nausea/vomiting, oedema, diarrhoea, mouth disorders and muscle disorders. CONCLUSIONS: The addition of selumetinib to fulvestrant did not show improving patients' outcome and was poorly tolerated at the recommended monotherapy dose. Selumetinib may have deteriorated the efficacy of the endocrine therapy in some patients.

Radiotherapy for GIST progressing during or after tyrosine kinase inhibitor therapy: A prospective study.

PURPOSE: Gastrointestinal stromal tumor (GIST) has been considered radiation-resistant, and radiotherapy is recommended only for palliation of bone metastases in current treatment guidelines. No registered prospective trial has evaluated GIST responsiveness to radiotherapy. PATIENTS AND METHODS: Patients with GIST progressing at intra-abdominal sites or the liver were entered to this prospective Phase II multicenter study (identifier NCT00515931). Metastases were treated with external beam radiotherapy using either conformal 3D planning or intensity modulated radiotherapy and conventional fractionation to a cumulative planning target volume dose of approximately 40Gy. Systemic therapy was maintained unaltered during the study. RESULTS: Of the 25 patients entered, 19 were on concomitant tyrosine kinase inhibitor therapy, most often imatinib. Two (8%) patients achieved partial remission, 20 (80%) had stable target lesion size for ⩾3months after radiotherapy with a median duration of stabilization of 16months, and 3 (12%) progressed. The median time to radiotherapy target lesion progression was 4-fold longer than the median time to GIST progression at any site (16 versus 4months). Radiotherapy was generally well tolerated. CONCLUSIONS: Responses to radiotherapy were infrequent, but most patients had durable stabilization of the target lesions. GIST patients with soft tissue metastases benefit frequently from radiotherapy.

Pregnancy outcome after TNF-α inhibitor therapy during the first trimester: a prospective multicentre cohort study.

AIMS: TNF-α inhibitors are considered relatively safe in pregnancy but experience is still limited. The aim of this study was to evaluate the risk of major birth defects, spontaneous abortion, preterm birth and reduced birth weight after first trimester exposure to TNF-α inhibitors. METHODS: Pregnancy outcomes of women on adalimumab, infliximab, etanercept, certolizumab pegol or golimumab were evaluated in a prospective observational cohort study and compared with outcomes of a non-exposed random sample. The samples were drawn from pregnancies identified by institutes collaborating in the European Network of Teratology Information Services. RESULTS: In total, 495 exposed and 1532 comparison pregnancies were contributed from nine countries. The risk of major birth defects was increased in the exposed (5.0%) compared with the non-exposed group (1.5%; adjusted odds ratio (ORadj ) 2.2, 95% CI 1.0, 4.8). The risk of preterm birth was increased (17.6%; ORadj 1.69, 95% CI 1.1, 2.5), but not the risk of spontaneous abortion (16.2%; adjusted hazard ratio [HRadj ] 1.06, 95% CI 0.7, 1.7). Birth weights adjusted for gestational age and sex were significantly lower in the exposed group compared to the non-exposed cohort (P = 0.02). As a diseased comparison group was not possible to ascertain, the influence of disease and treatment on birth weight and preterm birth could not be differentiated. CONCLUSIONS: TNF-α inhibitors may carry a risk of adverse pregnancy outcome of moderate clinical relevance. Considering the impact of insufficiently controlled autoimmune disease on the mother and the unborn child, TNF-α inhibitors may nevertheless be a treatment option in women with severe disease refractory to established immunomodulatory drugs.

Low levels of adherence with proton pump inhibitor therapy contribute to therapeutic failure in gastroesophageal reflux disease

To assess adherence to proton pump inhibitor (PPI) treatment and associated variables in patients with gastroesophageal reflux disease (GERD). Cross-sectional and prospective comprising 240 consecutive adult patients, diagnosed with GERD for whom continuous use of standard or double dose of omeprazole had been prescribed. Patients were ranked as ne-GERD (162: 67.5%) or e-GERD classified according to the Los Angeles classification as A (48:20.0%), B (21:8.6%), C (1:0.5%), D (1:0.5%), and Barrett's esophagus (7:2.9%). The Morisky questionnaire was applied to assess adherence to therapy and a GERD questionnaire to assess symptoms and their impact. Adherence was correlated with demographics, cotherapies, comorbidities, treatment duration, symptoms scores, endoscopic findings, and patient awareness of their disease. 126 patients (52.5%) exhibited high level of adherence and 114 (47.5%) low level. Youngers (P= 0.002) or married (O.R. 2.41, P= 0.03 vs. widowers) patients had lower levels of adherence; symptomatic patients exhibited lower adherence (P= 0.02). All other variables studied had no influence on adherence. Patients with GERD attending a tertiary referral hospital in Sao Paulo exhibited a high rate of low adherence to the prescribed PPI therapy that may play a role in the therapy failure. Age <60 years, marital status and being symptomatic were risk factors for low adherence.

Interferon-gamma release assays for latent tuberculosis infection in child and young adult candidates or recipients of tumor necrosis factor inhibitor therapy

Background. Inhibition of tumor necrosis factor (TNF) is associated with progression of latent tuberculosis infection (LTBI) to active disease. LTBI screening prior to starting TNF inhibitor therapy is recommended. Blood tests, collectively known as interferon-gamma release assays (IGRAs), offer a means other than the tuberculin skin test (TST) of screening for LTBI. However, in the setting of immune compromise, anergy may limit the clinical utility of IGRAs. ^ Methods. A cross-sectional study was conducted in children and young adults ≤ 21 years of age who were cared for at Texas Children's Hospital in Houston, TX, during 2011 and who were candidates for, or were receiving, tumor necrosis factor (TNF)-inhibitor therapy. All subjects answered a risk factor questionnaire and were tested for LTBI by two commercially available IGRAs (QuantiFERON-Gold In-Tube assay and the T-SPOT.TB assay), along with the TST. T-cell phenotypes were evaluated through flow cytometry, both at baseline and after antigen stimulation. ^ Results. Twenty-eight subjects were enrolled. All were TST negative and none were IGRA positive. Results were negative for the 27 subjects who were tested with QuantiFERON-Gold In-Tube. However, 26% of subjects demonstrated anergy in the T-SPOT.T. Patients with T-SPOT. TB anergy had lower quantitative IFN-γ responses to mitogen in the QFT assay—the mean IFN-γ level to mitogen in patients without T-SPOT.TB anergy was 9.84 IU/ml compared to 6.91 IU/ml in patients with T-SPOT.TB anergy (P = 0.046). Age and use of TNF inhibitors, corticosteroids, or methotrexate use were not significantly associated with T-SPOT.TB anergy. Antigen stimulation revealed depressed expression of intracellular IFN-γ in subjects with T-SPOT. TB anergy. ^ Conclusions. The frequency of anergy in this population is higher than would be expected from studies in adults. There appears to be inappropriate IFN-γ responses to antigen in subjects with T-SPOT. TB anergy. This immune defect was detected by the T-SPOT. TB assay but not by the QuantiFERON-Gold In-Tube assay. Further data are needed to clarify the utility of IGRAs in this population.^

Study on the effect of metformin in patients of metastatic renal cell cancer with diabetes receiving tyrosine kinase inhibitor therapy

Objective: The primary objective of our study was to study the effect of metformin in patients of metastatic renal cell cancer (mRCC) and diabetes who are on treatment with frontline therapy of tyrosine kinase inhibitors. The effect of therapy was described in terms of overall survival and progression free survival. Comparisons were made between group of patients receiving metformin versus group of patients receiving insulin in diabetic patients of metastatic renal cancer on frontline therapy. Exploratory analyses were also done comparing non-diabetic patients of metastatic renal cell cancer receiving frontline therapy compared to diabetic patients of metastatic renal cell cancer receiving metformin therapy. ^ Methods: The study design is a retrospective case series to elaborate the response rate of frontline therapy in combination with metformin for mRCC patients with type 2 diabetes mellitus. The cohort was selected from a database, which was generated for assessing the effect of tyrosine kinase inhibitor therapy associated hypertension in metastatic renal cell cancer at MD Anderson Cancer Center. Patients who had been started on frontline therapy for metastatic renal cell carcinoma from all ethnic and racial backgrounds were selected for the study. The exclusion criteria would be of patients who took frontline therapy for less than 3 months or were lost to follow-up. Our exposure variable was treatment with metformin, which comprised of patients who took metformin for the treatment of type 2 diabetes at any time of diagnosis of metastatic renal cell carcinoma. The outcomes assessed were last available follow-up or date of death for the overall survival and date of progression of disease from their radiological reports for time to progression. The response rates were compared by covariates that are known to be strongly associated with renal cell cancer. ^ Results: For our primary analyses between the insulin and metformin group, there were 82 patients, out of which 50 took insulin therapy and 32 took metformin therapy for type 2 diabetes. For our exploratory analysis, we compared 32 diabetic patients on metformin to 146 non-diabetic patients, not on metformin. Baseline characteristics were compared among the population. The time from the start of treatment until the date of progression of renal cell cancer and date of death or last follow-up were estimated for survival analysis. ^ In our primary analyses, there was a significant difference in the time to progression of patients receiving metformin therapy vs insulin therapy, which was also seen in our exploratory analyses. The median time to progression in primary analyses was 1259 days (95% CI: 659-1832 days) in patients on metformin therapy compared to 540 days (95% CI: 350-894) in patients who were receiving insulin therapy (p=0.024). The median time to progression in exploratory analyses was 1259 days (95% CI: 659-1832 days) in patients on metformin therapy compared to 279 days (95% CI: 202-372 days) in non-diabetic group (p-value <0.0001). ^ The median overall survival was 1004 days in metformin group (95% CI: 761-1212 days) compared to 816 days (95%CI: 558-1405 days) in insulin group (p-value<0.91). For the exploratory analyses, the median overall survival was 1004 days in metformin group (95% CI: 761-1212 days) compared to 766 days (95%CI: 649-965 days) in the non-diabetic group (p-value<0.78). Metformin was observed to increase the progression free survival in both the primary and exploratory analyses (HR=0.52 in metformin Vs insulin group and HR=0.36 in metformin Vs non-diabetic group, respectively). ^ Conclusion: In laboratory studies and a few clinical studies metformin has been proven to have dual benefits in patients suffering from cancer and type 2-diabetes via its action on the mammalian target of Rapamycin pathway and effect in decreasing blood sugar by increasing the sensitivity of the insulin receptors to insulin. Several studies in breast cancer patients have documented a beneficial effect (quantified by pathological remission of cancer) of metformin use in patients taking treatment for breast cancer therapy. Combination of metformin therapy in patients taking frontline therapy for renal cell cancer may provide a significant benefit in prolonging the overall survival in patients with metastatic renal cell cancer and diabetes. ^

Stochastic processes strongly influence HIV-1 evolution during suboptimal protease-inhibitor therapy

It has long been assumed that HIV-1 evolution is best described by deterministic evolutionary models because of the large population size. Recently, however, it was suggested that the effective population size (Ne) may be rather small, thereby allowing chance to influence evolution, a situation best described by a stochastic evolutionary model. To gain experimental evidence supporting one of the evolutionary models, we investigated whether the development of resistance to the protease inhibitor ritonavir affected the evolution of the env gene. Sequential serum samples from five patients treated with ritonavir were used for analysis of the protease gene and the V3 domain of the env gene. Multiple reverse transcription–PCR products were cloned, sequenced, and used to construct phylogenetic trees and to calculate the genetic variation and Ne. Genotypic resistance to ritonavir developed in all five patients, but each patient displayed a unique combination of mutations, indicating a stochastic element in the development of ritonavir resistance. Furthermore, development of resistance induced clear bottleneck effects in the env gene. The mean intrasample genetic variation, which ranged from 1.2% to 5.7% before treatment, decreased significantly (P < 0.025) during treatment. In agreement with these findings, Ne was estimated to be very small (500–15,000) compared with the total HIV-1 RNA copy number. This study combines three independent observations, strong population bottlenecking, small Ne, and selection of different combinations of protease-resistance mutations, all of which indicate that HIV-1 evolution is best described by a stochastic evolutionary model.

Prognostic Value of Dobutamine Stress Echocardiography With Early Injection of Atropine With Versus Without Chronic Beta-Blocker Therapy in Patients With Known or Suspected Coronary Heart Disease

Although a new protocol of dobutamine stress echocardiography with the early injection of atropine (EA-DSE) has been demonstrated to be useful in reducing adverse effects and increasing the number of effective tests and to have similar accuracy for detecting coronary artery disease (CAD) compared with conventional protocols, no data exist regarding its ability to predict long-term events. The aim of this study was to determine the prognostic value of EA-DSE and the effects of the long-term use of beta blockers on it. A retrospective evaluation of 844 patients who underwent EA-DSE for known or suspected CAD was performed; 309 (37%) were receiving beta blockers. During a median follow-up period of 24 months, 102 events (12%) occurred. On univariate analysis, predictors of events were the ejection fraction (p <0.001), male gender (p <0.001), previous myocardial infarction (p <0.001), angiotensin-converting enzyme inhibitor therapy (p = 0.021), calcium channel blocker therapy (p = 0.034), and abnormal results on EA-DSE (p <0.001). On multivariate analysis, the independent predictors of events were male gender (relative risk [RR] 1.78, 95% confidence interval [CI] 1.13 to 2.81, p = 0.013) and abnormal results on EA-DSE (RR 4.45, 95% CI 2.84 to 7.01, p <0.0001). Normal results on EA-DSE with P blockers were associated with a nonsignificant higher incidence of events than normal results on EA-DSE without beta blockers (RR 1.29, 95% CI 0.58 to 2.87, p = 0.54). Abnormal results on EA-DSE with beta blockers had an RR of 4.97 (95% CI 2.79 to 8.87, p <0.001) compared with normal results, while abnormal results on EA-DSE without beta blockers had an RR of 5.96 (95% CI 3.41 to 10.44, p <0.001) for events, with no difference between groups (p = 0.36). In conclusion, the detection of fixed or inducible wall motion abnormalities during EA-DSE was an independent predictor of long-term events in patients with known or suspected CAD. The prognostic value of EA-DSE was not affected by the long-term use of beta blockers. (C) 2008 Elsevier Inc. All rights reserved. (Am J Cardiol 2008;102:1291-1295)

Cost-effectiveness of pharmacogenetic testing to predict treatment response to angiotensin-converting enzyme inhibitor

OBJECTIVE: This study aimed to assess the potential cost-effectiveness of testing patients with nephropathies for the I/D polymorphism before starting angiotensin-converting enzyme (ACE) inhibitor therapy, using a 3-year time horizon and a healthcare perspective. METHODS: We used a combination of a decision analysis and Markov modeling technique to evaluate the potential economic value of this pharmacogenetic test by preventing unfavorable treatment in patients with nephropathies. The estimation of the predictive value of the I/D polymorphism is based on a systematic review showing that DD carriers tend to respond well to ACE inhibitors, while II carriers seem not to benefit adequately from this treatment. Data on the ACE inhibitor effectiveness in nephropathy were derived from the REIN (Ramipril Efficacy in Nephropathy) trial. We calculated the number of patients with end-stage renal disease (ESRD) prevented and the differences in the incremental costs and incremental effect expressed as life-years free of ESRD. A probabilistic sensitivity analysis was conducted to determine the robustness of the results. RESULTS: Compared with unselective treatment, testing patients for their ACE genotype could save 12 patients per 1000 from developing ESRD during the 3 years covered by the model. As the mean net cost savings was euro 356,000 per 1000 patient-years, and 9 life-years free of ESRD were gained, selective treatment seems to be dominant. CONCLUSION: The study suggests that genetic testing of the I/D polymorphism in patients with nephropathy before initiating ACE therapy will most likely be cost-effective, even if the risk for II carriers to develop ESRD when treated with ACE inhibitors is only 1.4% higher than for DD carriers. Further studies, however, are required to corroborate the difference in treatment response between ACE genotypes, before genetic testing can be justified in clinical practice.

Is there a correlation between venlafaxine therapy during pregnancy and a higher incidence of necrotizing enterocolitis?

BACKGROUND: Novel antidepressant drugs are increasingly used by women of child bearing age. However, potentially harmful effects on fetus and newborn remain unknown. METHODS: Case report and literature review. RESULTS: We present preterm twins whose mother was treated with venlafaxine, a nonselective serotonin reuptake inhibitor, throughout pregnancy until delivery. The twins developed neonatal necrotizing enterocolitis. CONCLUSION: The question whether there might be a correlation between maternal serotonin reuptake inhibitor therapy and neonatal necrotizing enterocolitis is discussed.

PARP Inhibitor Resistance - What Is Beyond BRCA1 or BRCA2 Restoration?

Nearly 10 years ago the usefulness of poly(ADP-ribose) polymerase (PARP) inhibitors to kill BRCA1 or BRCA2-deficient cells was reported, and this finding has served as a prime example of the concept of synthetic lethality in the context of anticancer therapy. The clinical translation of this finding has undergone several ups and downs, however. Despite spectacular responses seen in some patients with BRCA-deficient breast or ovarian cancers, other patients did not show the expected benefit from PARP inhibitor therapy. Thus, like for all novel tailored anti-cancer drugs, upfront and secondary resistance remain major hurdles in the implementation of the initial preclinical finding. We know at least one clinically relevant mechanism of PARP inhibitor resistance: the reversion of BRCA function by secondary mutations. Nevertheless, it is also clear that this mechanism does not explain all cases of resistance. At the moment, we only have a poor understanding of BRCA reversion-independent resistance mechanisms. Preclinical data have pointed in several directions, e.g. increased drug efflux, reduced drug target levels, or alternative DNA repair. Here, we discuss these mechanisms with a focus on potential DNA repair adaptations.

The Effect of Everolimus Initiation and Calcineurin Inhibitor Elimination on Cardiac Allograft Vasculopathy in De Novo Recipients: One-Year Results of a Scandinavian Randomized Trial.

Early initiation of everolimus with calcineurin inhibitor therapy has been shown to reduce the progression of cardiac allograft vasculopathy (CAV) in de novo heart transplant recipients. The effect of de novo everolimus therapy and early total elimination of calcineurin inhibitor therapy has, however, not been investigated and is relevant given the morbidity and lack of efficacy of current protocols in preventing CAV. This 12-month multicenter Scandinavian trial randomized 115 de novo heart transplant recipients to everolimus with complete calcineurin inhibitor elimination 7-11 weeks after HTx or standard cyclosporine immunosuppression. Ninety-five (83%) patients had matched intravascular ultrasound examinations at baseline and 12 months. Mean (± SD) recipient age was 49.9 ± 13.1 years. The everolimus group (n = 47) demonstrated significantly reduced CAV progression as compared to the calcineurin inhibitor group (n = 48) (ΔMaximal Intimal Thickness 0.03 ± 0.06 and 0.08 ± 0.12 mm, ΔPercent Atheroma Volume 1.3 ± 2.3 and 4.2 ± 5.0%, ΔTotal Atheroma Volume 1.1 ± 19.2 mm(3) and 13.8 ± 28.0 mm(3) [all p-values ≤ 0.01]). Everolimus patients also had a significantly greater decline in levels of soluble tumor necrosis factor receptor-1 as compared to the calcineurin inhibitor group (p = 0.02). These preliminary results suggest that an everolimus-based CNI-free can potentially be considered in suitable de novo HTx recipients.

Female melanoma: the role of ovarian stimulation and antioestrogens cancer therapy A retrospective study with immunohistochemical oestrogen receptors alpha and beta analysis.

Cutaneous melanoma (CM) represents the third most common cancer in Italian women under 49 years old. In the last decades, many molecular studies confirmed that sex hormones have a part in melanogenesis and melanoma genesis. However, many controversies are present regarding the role of exogenous oestrogens intake and endogenous hormonal status in female melanoma. Our study's primary objective is to investigate the features of melanoma in women of fertile age and women in postmenopausal age. The secondary aim is to evaluate the expression of ERα and ERβ by immunohistochemical analysis in women who underwent ovarian stimulation for medically assisted procreation and in women in cancer therapy for breast cancer (BC) comparing to two control groups. The tertiary objective is to correlate ERα and ERβ with the Breslow thickness and other relevant histopathological, clinical and dermoscopic characteristics Results A total of 998 women were included in the study. Women in fertile age are significantly more prone to have CM on the trunk. Conversely, postmenopausal females are more likely to develop CM on acral locations. Breslow thickness and ulceration were statistically significant among postmenopausal women (P-value <0,001). In the group for women with a history of breast cancer (BC), we observed a significantly higher CM percentage with “non-brisk” TILs. Upon immunohistochemical analysis, most cases with inhibitor aromatase therapy displayed a strong cytoplasmatic ERα positivity. Upon the Pearson correlation analysis, no association was shown between nuclear ERβ and Breslow thickness. The meaning of cytoplasmatic ERα in melanoma is still debated. It could suggest a potentially significant role of oestrogen non-genomic pathway in these patients, or it can be a mechanism of ERs modulation in response to aromatase inhibitor therapy. Our work tried to enlighten some of the existing shadows on the role of ERs and hormonal factors in CM.

Timing of Dose Relative to Sexual Intercourse Attempt in Previous Sildenafil Citrate Users Treated with Tadalafil: A Geographical Comparison from a Single Arm, Open-Label Study

Introduction. Previous research has demonstrated that sildenafil citrate users alter dosing-sexual attempt behavior when switched to tadalafil. The impact of geography and culture on sexual behavior with phosphodiesterase type 5 (PDE5) inhibitor treatment has not been fully investigated. Aim. To describe and compare the changes in dosing-sexual attempt behavior with sildenafil citrate vs. tadalafil treatment across four distinct geographies: Asia, Australia/New Zealand (ANZ), Central Eastern Europe/Middle East (CEE/ME), and Latin America (LA). Methods. Data from a single-arm, open-label clinical trial conducted in 21 countries from November 2002 to May 2004 were used in this analysis. Men with erectile dysfunction and a history of >= 6-week prior sildenafil citrate use continued sildenafil citrate treatment for 4 weeks then switched to tadalafil for 8 weeks. Dosing instructions were provided. Main Outcomes Measures. Timing of dose and sexual intercourse was assessed through patient diaries for the final 4 weeks of each treatment period. Results. A total of 2,760 men were enrolled: Asia 15.8%; ANZ 29.4%; CEE/ME 19.7%; LA 35.1%. The median time from dosing to intercourse was significantly increased during tadalafil treatment across all geographical regions; however, the magnitude of increase differed significantly by geography (P < 0.0001). The Asian cohort demonstrated the shortest duration between dosing and sexual intercourse attempts (irrespective of drug), and altered sexual behavior the least upon switching to tadalafil. The ANZ cohort demonstrated the longest duration between dosing and sexual intercourse attempts (irrespective of drug), and altered sexual behavior the most upon switching to tadalafil. Conclusion. Men with a history of established sildenafil citrate use alter their dose-attempt behavior when treated with tadalafil irrespective of geography. However, the extent to which sexual behavior alters is not uniform across geographical regions, suggesting that dosing instructions and duration of drug effectiveness, in combination with personal and cultural preferences, may determine sexual behavior with PDE5 inhibitor use. Rubio-Aurioles E, Glina S, Abdo CHN, Hernandez-Serrano R, Rampazzo C, Sotomayor M, West TM, Gallagher GL, and Lenero E. Timing of dose relative to sexual intercourse attempt in previous sildenafil citrate users treated with tadalafil: A geographical comparison from a single arm, open-label study. J Sex Med 2009;6:2836-2850.